Boyfriend told my friend's boyfriend this?

So me and my boyfriend went on a double date with my best friend and her boyfriend. We went to the movies altogether. Before going into the cinema, I went with my best friend to get something in a shop and so my boyfriend and her boyfriend was together and just talking. When we got back, we went inside the cinema. The next day, I met up with my best friend. She told me that her boyfriend asked my boyfriend questions such as "how long have you been with her (me)?" and he said "7 months, and this is the longest relationship he's been in (our relationship)" and then she told me that my boyfriend said to her boyfriend "i love her"Would he lie about that? Why would he say that out of no where?